what are the influences in macbeth's life that led to his eventual downfall

I think we that we need to consider that nobody made Macbeth do anything. Macbeth's tragic flaw, all protagonists in all tragedies have a tragic flaw, is his greed and ambition combined with the fact that he is kind of a coward. He stumbles his way through successive murders until he becomes King. Unfortunately by that time, he has pretty much sold his soul and become a socio-path that nobody likes.

I think as far as the witches are concerned, they were meant to be a catalyst for Macbeth to help bring him over to his "dark and deep desires". To be sure Witches were considered evil at the time by Elizabethans so they have all the trademarks of Devil worship and the black arts. So yes they were "bad" but I think Macbeth was the one who was really wicked to begin with.

Oh yes his wife. She definitely was a force in his life. Like the witches, L Macbeth is a catalyst who spurs her husband on. Pretty soon though Macbeth needs no help at all in becoming the socio-path we all know.